First time backpacking

I'm going to make plans for a trip, I'm not sure where though, so I need some tipsand advicr for first time travellers, I have nobody to go with, so I will mostly be alone, I been abroad before, I'm half American half British and live in the UK.

I don't know how my social anxiety and generalise anxiety will impact my choices. I done CBT, I do know how to manage the anxiety attacks, but confidence and pushing myself is tough.

There 7 places out of my list, Spain, Germany, Iceland Scotland Australia and New Zealand.

I was hoping to do the working holiday visa, but never had the courage to do it, I'm 29 years old now. 30 in October. I like to do something when I travel, something more than sight seeing and seeing wildlife and historic places which I am passionate about doing work or volunteering.

couchsurfing.com - Hosts offer free temporary housing. Most hosts are good, warm, welcoming people who just want to chat and learn about your travels, but occasionally you'll find a creepy host, and you're faced with a decision of whether or not you want to flee the only housing you have available. Be careful.
workaway.info - How to earn money while traveling outside of your homeland.

I trust you know about craigslist.org, for virtually all your travel needs.

And other than that, I, myself, am planning a trip to Iceland and Spain to begin in May! Iceland has a penis museum, undersea caves, and tectonic plate action. And it's cold. Backpacking Spain's "El Camino de Santiago" is supposed to be gorgeous, enlightening, life-changing. And the Spanish have a reputation for being warm and welcoming.

I've been to Australia & New Zealand, but this was over a decade ago. If it still exists, I recommend Auckland's MERC: I think that stands for Marine Education Recreation Center? But I was but a teen when I visited.

Also, it's probably safer to start with baby steps. Make your first trip abroad a little one. You'll probably learn a lot. And you'll be better equipped for your next trip, since you learned from your first trip.